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#include <bits/stdc++.h>
using namespace std;

#define mp make_pair
#define pb push_back
#define st first
#define nd second
#define fi first
#define se second
#define vt vector
#define FOR(a, b, c)  for(int a=b; a<c; ++a)
#define all(a)     (a).begin(),(a).end()
#define sz(a)      (int)(a).size()

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef vector<int> vi; 
typedef vector<ll> vll;
typedef pii PII;
typedef pll PLL;

constexpr ll nax = 2e5+6969, INF = 1e9+2137;
constexpr ld eps = 1e-9;

mt19937_64 rng(6969);
// mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());

inline ll rand(ll l, ll r) {
	return uniform_int_distribution<ll>(l, r)(rng);
}

ll n, m, s; 

int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    cin >> n >> m >> s; 
    vector<pll> v(m); 
    for(auto &e: v) {
        cin >> e.fi >> e.se; 
    }
    sort(all(v)); 

    ll dis = n * 2; 
    ll ans = -1; 

    for(int i = 0; i < m; i++) {
        if(s > v[i].se)
            continue; 
        int cur = i; 
        while(cur > 0 && v[cur-1].se + 1 == v[cur].fi)
            cur--; 
        if(v[cur].fi > 1) {
            if(dis > s - (v[cur].fi - 1)) {
                dis = s - (v[cur].fi - 1); 
                ans = v[cur].fi - 1; 
            }
        }

        cur = i; 

        while(cur < m && v[cur+1].fi - 1 == v[cur].se)
            cur++; 
        if(v[cur].se < n) {
            if(dis > (v[cur].se + 1) - s) {
                dis = (v[cur].se + 1) - s; 
                ans = v[cur].se + 1; 
            }
        }

        break; 
    }

    cout << ans << "\n"; 

    return 0;
}